48 V Li-ion Battery and it's Battery Management System

           So as I promised in the previous post, this post is regarding the making of a 48 V battery and how it is interfaced with a Battery Management System. So what is a battery management system or a BMS and what are the functions associated with it ?

                                     

Battery Management System (BMS)

                                A Battery Management System is any circuit that tries to manage a rechargeable battery by making sure it is maintained to operate in its safe operational region, by collecting data about the operations in the battery, by controlling the conditions it is surrounded by, and by reporting this data. 

The next question is why a BMS is considered to be a mandate in the case of Li-ion battery ?

The answer is simple. A Li-ion battery if not operated at it's safe operational ranges can prove to be hazardous. This is the reason why a BMS is considered as a mandate in the case of a Li-ion battery.

So why not go for other batteries which require a less complex BMS ? 

There isn't a much better battery as of now that is quite good when it comes to delivering power required for applications that need a high amount of power. Research is still going on in the field of new battery technologies that can possibly replace the high risk factor involved with Li-ion batteries.

So what did we manage to do in our project ?     

My team members include Allen Thomas, Akhil Biju, and myself Jose Thomas. We assembled a 48 V Li-ion battery with 39 Samsung ICR 18650 cells using solderless battery pack assembly kit and we also managed to interface this battery with a 48 V, 60 A BMS. The BMS can be connected to the PC or to a smartphone using Bluetooth and hence can be used to find all information related to the battery such as voltage of individual cells, terminal voltage, temperature it is being exposed to, etc.

Info on 48 V Li-ion battery obtained via the BMS connected to the PC by Bluetooth

The voltage of each cell is 3.7 V and 2600 mAh. So connecting 13 cells in series gave us a terminal voltage of 48.1 volts. Connecting 3 of such, 13 cells in series, in parallel got us a current of 7800 mAh. Thereby making a 48 V, 7800 mAh rated battery. 

Video of Allen explaining about the making of the battery and the functions of BMS:

The making of the 48 V battery and interfacing it with the 48 V, 60 A BMS:

Not much is known about battery technology in our country and this was our first attempt to try and develop some knowledge in the emerging field of battery technology, so that we could make our contributions to this field and also share what we learned with others. This battery pack was made for the Electric bike that we had made. The details of which will be posted in the next post. So stay tuned.